Getting Started

Jint.Workflows lets you write long-running orchestration logic as JavaScript async functions, suspend at any point, persist the state, and resume later — potentially days later, in a different process.

Install

dotnet add package Jint.Workflows

Requires .NET 10.0+ and Jint 4.7.1+.

Hello, workflow

using Jint.Workflows;

var workflow = new WorkflowEngine();
workflow.RegisterSuspendFunction("sleep", args => DurationParser.Parse(args[0]));

var script = """
    async function main() {
        await sleep('5s');
        return 'done';
    }
""";

var result = workflow.RunWorkflow(script, "main");
// result.Status == Suspended
// result.Suspension.FunctionName == "sleep"
// result.Suspension.ResumeAt ≈ 5 seconds from now

The workflow suspended at await sleep('5s'). It's waiting. Your orchestrator decides when to resume:

// Persist the state somewhere
string json = result.State!.Serialize();

// ... 5 seconds later
var resumed = workflow.ResumeWorkflow(script, json);
// resumed.Status == Completed
// resumed.Value.AsString() == "done"

Step functions — journaled side effects

Register a C# function that gets called from JavaScript. The result is cached in the journal so it never re-runs on replay.

workflow.RegisterStepFunction("fetchUser", args =>
    userService.GetById((string)args[0]!));

async function main(userId) {
    const user = await fetchUser(userId);   // runs once, cached on replay
    await sleep('1d');
    return user.name;
}

On resume, fetchUser returns the cached result without hitting the database again — even though the script re-executes from the top.

Suspend functions — wait for something external

Register a name that, when awaited, pauses the workflow. The orchestrator chooses when to resume and what value to deliver.

workflow.RegisterSuspendFunction("getApproval");

async function main(orderId) {
    const approved = await getApproval('manager', orderId);
    return approved ? 'shipped' : 'cancelled';
}

When execution reaches await getApproval(...), the workflow suspends. The caller resumes with a value:

var result = workflow.RunWorkflow(script, "main", "ORD-001");
// result.Suspension.FunctionName == "getApproval"
// result.Suspension.Arguments == ["manager", "ORD-001"]

// ...approval arrives
var completed = workflow.ResumeWorkflow(script, result.State!, resumeValue: true);
// completed.Value.AsString() == "shipped"

Next steps

• How It Works — the replay model and why it's safe
• Step Functions — retries, policies, error handling
• Suspending Execution — sleep, waitForEvent, and custom suspends
• HTTP with fetch — opt-in browser-compatible fetch
• Versioning — safe script edits between suspensions